The present invention relates to a magnetic field sensor, and more particularly to a magnetic field sensor suitable for sensing a magnetic field generated by an objective one of interconnections formed at a high density without receiving any substantive influence of a magnetic field generated by an adjacent interconnection positioned very close to the objective interconnection.
Various types of the magnetic field detectors have been proposed to measure the magnetic field generated by the interconnection on the printed circuit boards. A semi-rigid coaxial line shielded loop magnetic field detector is disclosed in xe2x80x9cIEEE Transactions on Antenna and Propagationxe2x80x9d vol. AP-21, No. 4, pp. 446-461, July 1973. This semi-rigid coaxial line shielded loop magnetic field detector is illustrated in FIG. 1. This semi-rigid coaxial line shielded loop magnetic field detector comprises a coaxial line in the form of a circular-shaped loop. The right half of the semi-rigid coaxial line shielded loop magnetic field detector comprises a coaxial line 51 which is half-circular shaped, wherein an end of the coaxial line 51 is positioned at the bottom of the circular-shaped loop, where a center conductive line 53 is striped thereby to form a gap 14 at the bottom of the circular-shaped loop. The left half of the semi-rigid coaxial line shielded loop magnetic field detector comprises a conductive line 52 which provides an electrical connection between the center conductive line 53 to an external line.
In measurement of the magnetic field generated by the objective interconnection 54, the semi-rigid coaxial line shielded loop magnetic field detector is positioned just over the objective interconnection 54 so that the circular-shaped dielectric looped face is in parallel to the objective interconnection 54, whereby magnetic flux generated by the objective interconnection 54 penetrates the circular-shaped dielectric looped face. As a result, a voltage output signal can be obtained from the semi-rigid coaxial line shielded loop magnetic field detector.
Another type of the magnetic field detector is disclosed in xe2x80x9cIEEE Transactions on Magneticsxe2x80x9d vol. 32, No. 5, pp. 4941-4943, September 1996.
The first conventional detector is unsuitable for selectively detecting a magnetic field generated by an objective interconnection 54 only without receiving any substantive influence of a magnetic field generated by an adjacent interconnection 55 positioned very close to the objective interconnection 54 as illustrated in FIG. 2. The dielectric looped face of the detector receives the superimposed magnetic fields of the objective and adjacent interconnections 54 and 55.
In order to solve the above problem, it is required to approach the loop center of the detector as close to the objective interconnection 54 as possible. A pitch of the adjacent two of the interconnections on the printed circuit board is very narrow, for example, 0.1 millimeter order. Notwithstanding, the first conventional semi-rigid coaxial line shielded loop magnetic field detector is hared to be scaled down due to difficulty in keeping a mechanical strength of the loop and not so small diameter of coaxial line of about 1 millimeter. The first conventional semi-rigid coaxial line shielded loop magnetic field detector is hand-made. This further makes it difficult to scale down of the detector.
In the meantime, the second conventional sensor comprises a planer circuit which is relatively suitable for scaling down the detector. Notwithstanding, the second conventional sensor is hard to be connected directly to a measuring apparatus without using a jig. The use of the jig for connecting the external coaxial line to the sensor makes it inconvenient to position the loop center as close to the objective interconnection as required to selectively detect the magnetic field of the objective interconnection only without receiving any influence due to the disturbing magnetic field generated by the adjacent interconnection.
In the above circumstances, it had been required to develop a novel magnetic field detector free from the above problems.
Accordingly, it is an object of the present invention to provide a novel device for detecting a magnetic field free from the above problems.
It is a further object of the present invention to provide a novel device for detecting a magnetic field, which is largely scaled down to enable a dielectric looped face to be positioned adjacent to an objective source of generating a magnetic field to be detected.
It is a still further object of the present invention to provide a novel device for detecting only a magnetic field generated by an objective magnetic field generating source.
It is yet a further object of the present invention to provide a novel device for detecting a magnetic field which is highly sensitive.
It is a further more object of the present invention to provide a novel device for detecting a magnetic field which is capable of electrically and mechanically secure connection to an external coaxial line.
The present invention provides a device for detecting a magnetic field comprising: a dielectric body; an electrically conductive pattern; and an electrically conductive ground region. The electrically conductive pattern so extends in the dielectric body as to form a dielectric looped face at least partially surrounded by the electrically conductive pattern, and the electrically conductive pattern having a first end electrically connected to an external electrically conductive line and a second end. The electrically conductive ground region is formed in the dielectric body. The electrically conductive ground region is electrically connected to the second end of the electrically conductive pattern and is electrically isolated from other parts of the electrically conductive pattern than the second end, so that the electrically conductive ground region serves as a ground to the electrically conductive pattern.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.